feat(shorebird_cli): add account apps subcommand

[nickshorebird]

Summary

• Adds shorebird account apps, which lists apps the current user has access to. Mirrors the account orgs shape so the account namespace stays parallel (whoami, orgs, apps).
• Pure CLI add. Reuses the existing codePushClientWrapper.getApps() already used internally by release/patch flows. No new wrapper, protocol, or server work.
• Human output: space-separated app_id display_name latest_release_version latest_patch_number, w/ - for unreleased apps. --json returns { apps: [{ app_id, display_name, latest_release_version, latest_patch_number }] }.
• Help-text column labels match JSON keys verbatim, so an agent reading --help and then parsing --json sees identical field names. Caught while comparing the three account subcommands' help output side-by-side.
• Closes the last CLI-only gap in the account surface from the agentic smoke test. Remaining account capabilities (org create, member mgmt, API keys, usage/plan, audit logs, transfer-app-to-org) all need backend work and will land separately.

Why not a plain app command?

I originally planned to have app, eg shorebird app, but each of the app commands are either semantically covered already, eg create w/ release, or logically fit better into account or other parents.

Testing

• 10 new tests in apps_command_test.dart: precondition failure, auth required, populated and empty-state human output, API-error path in human and JSON modes, JSON success shape w/ flat fields, projection check (no created_at/updated_at leak), empty-array case
• dart test packages/shorebird_cli: 2028 passed, 1 skipped (pre-existing), 0 failures
• dart analyze --fatal-warnings lib test: clean on new files
• dart format: clean
• Manual smoke against an authenticated dev environment: shorebird account apps and shorebird account apps --json both render correctly; forced-unauthenticated path returns the expected JSON error envelope

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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